In general, this invention relates to laser-aided direct material deposition processes and, more particularly, to a system and method of monitoring, controlling and modifying such processes, preferably in real time, from a remote location.
Advances in modem telecommunication methods, including the Internet, as well as advances in data acquisition and manipulation, allow the transfer of large volumes of data between distant sites in a relatively short time. The use of web browsers enable users to view not only text, but also video, graphics and audio files.
Large data files may be compressed before their transfer by a variety of methods to speed transmission time. Connections between sites may be effected by high-speed links in asynchronous transfer mode (ATM) or using Ethernet and Fast-Ethernet in a Local Access Network (LAN) or Wide Access Network (WAN) environment.
Interactive image and data transmission is currently under development for various applications including medical examination, diagnosis and treatment of disease, as described in U.S. Pat. No. 6,021,404 (Universal computer assisted diagnosis), U.S. Pat. No. 6,055,487 (Interactive remote sample analysis system) and U.S. Pat. No. 6,047,259 (Interactive method and system for managing physical exams, diagnosis and treatment protocols in health care practice).
Another remote control application is related to remote access and exchange of data between a remote host and an instrument, such as the vector modulation analyzer (VMA) with resident control and data acquisition software, as described in U.S. Pat. No. 5,790,977.
The need remains, however, for a system and method enabling a design team at a remote site to monitor, control and modify the fabrication process of a product at a local manufacturing site. Such tele-control would be particularly advantageous when the manufacturing process involves specialized and delicately calibrated or expensive equipment, which is either too costly to duplicate at many plants or simply not available at the chosen or required site of production.
This invention utilizes advances in telecommunication and fast data transfer to control the fabrication of precisely dimensioned and intricately-detailed products through an automated, feedback-controlled, laser-aided direct material deposition (DMD) process, as described in co-owned and co-pending U.S. patent application Ser. No. 09/107,912, filed Apr. 10, 1997, and in U.S. patent application Ser. No. 09/522,671, filed Mar. 10, 2000.
The geometry of the product is provided by a computer-aided design system (CAD). The deposition tool path is generated by a computer-aided manufacturing system (CAM) for CNC machining having post-processing software for deposition, instead of software for removal, as in conventional CNC machining. The CAM software interfaces with a feedback controller. For in-situ control of the DMD manufacturing process, the computer holding the CAD/CAM software, the CNC and feedback controller and the laser equipment are all located at the local manufacturing site.
For remote control of the DMD process, a design team or an individual designer is located at the xe2x80x9cremotexe2x80x9d site and operates, through a user interface, their xe2x80x9cremotexe2x80x9d host computer. The remote computer stores the description of a product to be fabricated. The description is preferably processed by a commercial Computer-Aided Design and Computer-Aided Manufacturing (CAD/CAM) software package, also residing at the remote host computer. This software generates a CAM file from which the tool path file will be created.
Because the CAM file of the product description is large, it is first compressed by an efficient compression algorithm to enable its fast transmission, e.g. over the Internet, to the manufacturing site. The remote host computer is preferably equipped with two monitors, one with a graphical user interface and the other for image and video observation of the laser-aided direct material deposition process. The display preferably includes zoom and rotation capabilities to enable detailed and accurate view from various angles of the product undergoing fabrication.
When the designer perceives a defect, an abnormality or some other undesirable characteristic affecting the final quality of the product, or when it seems desirable to improve the design, the designer may pause or abort the fabrication process by sending a command to the controller of the DMD system at the xe2x80x9clocalxe2x80x9d, i.e. the manufacturing, site. The designer then edits the CAD file and transmits over the Internet the modified and post-processed CAM file, either in its entirety, or only a block of it containing the modification.
Optical sensors at the manufacturing site continuously monitor the composition, temperature, and dimensions of the product. Acoustic emission sensors and strain gages at the manufacturing site monitor residual stress development in the product. Some or all of the information from the sensors is sent via a communications system to the remote computer at the designer site to determine the need for corrective measures. The signals from the sensors are also sent to the local computer control system at the manufacturing site, where they are further processed to determine the independent parameters controlling the DMD process, e.g. the laser power, the beam diameter and the powder flow rate. The feedback controller uses this information to control the laser deposition process on command from the remote computer transmitted to the feedback controller through the local computer.